How many PCs do you need so that you can sit next to your friend?

In our Learning Resources Centre we have 190 PCs.  They are spread over the three floors of the LRC in approximately equal numbers.  We operate a booking system using MyPC which works well - students come up to the appropriate desk / counter on the floor that they wish to work on and ask to be booked onto a PC.  We are always busy but rarely at absolute capacity.  This is because most of our students want to sit next to their friends when they are working so we are always booking in 2s or 3s which sometimes leaves us with odd ones.  We try lots of ways to optimise every space but to no avail - it is a social / cultural thing - even when working it is important to be with friends and be able to easily communicate